Wireless communication apparatus, wireless communication method, computer program, and wireless communication system

ABSTRACT

A wireless communication apparatus includes: a first wireless communication section performing wireless communication on the basis of a first communication mode; a second wireless communication section performing wireless communication on the basis of a second communication mode using a different frequency band from the first communication mode; a beam learning signal generation section generating a beam learning signal for specifying a beam pattern at the time of the communication based on the second communication mode and transmitting the beam learning signal from the second wireless communication section; a response information acquisition section acquiring response information responding to the transmitted beam learning signal; and a preliminary information generation section generating preliminary information so as not to cause interference among a plurality of wireless communications using the second communication mode on the basis of the response information and transmitting the preliminary information from the first wireless communication section.

This application is a divisional of U.S. application Ser. No.12/730,744, filed Mar. 24, 2010 and entitled “Wireless CommunicationApparatus, Wireless Communication Method, Computer Program, and WirelessCommunication System.”

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wireless communication apparatus, awireless communication method, a computer program, and a wirelesscommunication system. Specifically, for example, the invention relatesto a wireless communication apparatus, which performs communicationusing a millimeter wave by directing the beam of the directional antennato the direction of the communication target location, a wirelesscommunication method therefor, a computer program therefor, and awireless communication system using the same.

2. Description of the Related Art

In wireless communication, there have been developments in technologiesof millimeter-wave communication for promoting utility, such aslarge-volume and long-distance transmission, a decrease in size ofwireless equipment, and reduction in cost, and which have been mainlyused for short distance wireless access communication, imagetransmission systems, simple wireless communication, anti-collisionradars for vehicles, and the like. The wavelength of the millimeter waveis in the range of 1 mm to 10 mm, which corresponds to 30 GHz to 300 GHzin terms of frequency. For example, in the wireless communication usinga 60 GHz band, it is possible to allocate a channel in units of GHz, andit is also possible to perform high-speed data communication.

The millimeter wave has a short wavelength and excellent straightness,and enables transmission of very large volume of information, ascompared with the microwave having come into widespread use in thewireless LAN (Local Area Network) technology. In contrast, since themillimeter wave is rapidly attenuated in accordance with reflection, thedirect wave thereof or the just one-time reflected wave is mainly usedas a path of the wireless communication. In addition, since themillimeter wave has a large propagation loss, the millimeter wave has aproperty that the wireless signal does not reach far.

To complement the problem in the reach distance of the millimeter wave,a method is conceivable in which directivity is provided to the antennaof the transceiver and the communication distance is increased bydirecting the transmission beam and reception beam of the antenna to thedirection of the communication target location. The directivity of thebeam can be controlled, for example, in a way that a plurality ofantennas are respectively provided to the transceivers and the weightingof transmission or the weighting of reception is changed for eachantenna. In the millimeter wave, the reflected wave is scarcely used,and thus the direct wave becomes important. From this point, it isconceivable to use a directional beam which is pointed. In addition, theoptimal directivity of the antenna is learned, and then themillimeter-wave wireless communication may be performed.

In the millimeter-wave communication, for example, the direction of thetransmission antenna is determined by transmitting a signal fordetermining the direction of the directivity of the transmission antennaby using the second communication unit using the communication based onany one of electric line communication, optical communication, and soundwave communication. Further, there have been proposed wirelesstransmission systems for performing wireless transmission between thetransceivers by using the first communication unit using the electricwave of 10 GHz or more after the determination of the direction of theantenna (for example, refer to Japanese Patent Nos. 3544891 and3333117).

Further, the method of increasing the communication distance by usingthe directivity of the antenna is also applied to the IEEE802.15.3cwhich is the standard of the wireless PAN (mmWPAN: millimeter-waveWireless Personal Area Network) using the millimeter wave band.

SUMMARY OF THE INVENTION

By the way, even in the wireless communication system configured toprovide the directivity to the antenna of the transceiver and performcommunication by directing the transmission beam and reception beam tothe direction of the communication target location, there is anunnecessary process such as retransmission performed when interferenceoccurs in the system during the wireless communication. Accordingly,information (hereinafter, referred to as “preliminary information”)representing the transmission/reception schedule and the like isprovided in advance to the wireless communication apparatus before thecommunication, and then wireless communication is performed on the basisof the preliminary information, thereby enabling efficient communicationwithout causing retransmission. However, unless the wirelesscommunication of the preliminary information has high reliability, it isdifficult to perform efficient wireless communication without generatingan unnecessary process.

Accordingly, in the embodiments of the invention, it is desirable toprovide a wireless communication apparatus capable of performingefficient wireless communication by performing reliable communication onthe preliminary information. In addition, it is also desirable toprovide a wireless communication method therefor, a computer programtherefor, and a wireless communication system using the same.

According to the first embodiment of the invention, a wirelesscommunication apparatus includes: a first wireless communication sectionperforming wireless communication on the basis of a first communicationmode; a second wireless communication section performing wirelesscommunication on the basis of a second communication mode using adifferent frequency band from the first communication mode; a beamlearning signal generation section generating a beam learning signal forspecifying a beam pattern at the time of the communication based on thesecond communication mode and transmitting the beam learning signal fromthe second wireless communication section; a response informationacquisition section acquiring response information responding to thetransmitted beam learning signal; and a preliminary informationgeneration section generating preliminary information so as not to causeinterference among a plurality of wireless communications using thesecond communication mode on the basis of the response information andtransmitting the preliminary information from the first wirelesscommunication section.

In the embodiment of the invention, for example, the wirelesscommunication is performed in the first communication mode of afrequency channel less than 10 GHz and in the second communication modeof a frequency channel equal to or more than 10 GHz. Further, the beamlearning signal enabling identification as to which beam pattern is usedin the transmission thereof is generated, and the beam learning signalis transmitted with the beam pattern based on the beam learning signalin the second communication mode. Then, on the basis of the responseinformation responding to the beam learning signal, the communicationschedule is set so that the plurality of wireless communications areperformed at the same time in the second communication mode. Thus, thepreliminary information including the communication schedule issimultaneously or separately transmitted to the plurality of wirelesscommunication apparatuses in the first communication mode.

According to a second embodiment of the invention, a wirelesscommunication apparatus includes: a first wireless communication sectionperforming wireless communication on the basis of a first communicationmode; a second wireless communication section performing wirelesscommunication on the basis of a second communication mode using adifferent frequency band from the first communication mode; a receptionsituation monitoring section receiving a beam learning signaltransmitted in the second communication mode in order to specify a beampattern at the time of the communication based on the secondcommunication mode, and monitoring a reception situation for each beampattern; and a response information generation section generating andtransmitting response information on the basis of the monitoring resultof the reception situation.

In the embodiment of the invention, when the beam learning signaltransmitted in the second communication mode is received, the receptionsituation is monitored for each beam pattern. Thereby, the responseinformation including information enabling identification as to the beampattern by which the reception situation is optimized is generated andtransmitted. Further, the response information includes informationrepresenting the available wireless communication apparatus. Inaddition, the beam learning signal for specifying the beam pattern atthe time of the communication based on the second communication mode isgenerated, and transmitted together with the response information in thesecond communication mode.

According to a third embodiment of the invention, a wirelesscommunication method includes the steps of: performing wirelesscommunication on the basis of a first communication mode, by using afirst wireless communication section; performing wireless communicationon the basis of a second communication mode using a different frequencyband from the first communication mode, by using a second wirelesscommunication section; generating a beam learning signal for specifyinga beam pattern at the time of the communication based on the secondcommunication mode and transmitting the beam learning signal from thesecond wireless communication section, by using a beam learning signalgeneration section; acquiring response information responding to thetransmitted beam learning signal, by using a response informationacquisition section; and generating preliminary information so as not tocause interference among a plurality of wireless communications usingthe second communication mode on the basis of the response informationand transmitting the preliminary information from the first wirelesscommunication section, by using a preliminary information generationsection.

According to the fourth embodiment of the invention, a wirelesscommunication method includes the steps of: performing wirelesscommunication on the basis of a first communication mode, by using afirst wireless communication section; performing wireless communicationon the basis of a second communication mode using a different frequencyband from the first communication mode, by using a second wirelesscommunication section; receiving a beam learning signal transmitted inthe second communication mode in order to specify a beam pattern at thetime of the communication based on the second communication mode, andmonitoring a reception situation for each beam pattern, by using areception situation monitoring section; and generating and transmittingresponse information on the basis of the monitoring result of thereception situation, by using a response information generation section.

According to a fifth embodiment of the invention, a computer programcauses a computer to execute a communication process in a communicationapparatus including a first wireless communication section performingwireless communication on the basis of a first communication mode and asecond wireless communication section performing wireless communicationon the basis of a second communication mode using a different frequencyband from the first communication mode. The computer program causes thecomputer to function as: means for performing wireless communication onthe basis of the first communication mode by using the first wirelesscommunication section; means for performing wireless communication onthe basis of the second communication mode using a different frequencyband from the first communication mode by using the second wirelesscommunication section; means for generating a beam learning signal forspecifying a beam pattern at the time of the communication based on thesecond communication mode and transmitting the beam learning signal fromthe second wireless communication section; means for acquiring responseinformation responding to the transmitted beam learning signal; andmeans for generating preliminary information so as not to causeinterference among a plurality of wireless communications using thesecond communication mode on the basis of the response information andtransmitting the preliminary information from the first wirelesscommunication section.

According to a sixth embodiment of the invention, a computer programcauses a computer to execute a communication process in a communicationapparatus including a first wireless communication section performingwireless communication on the basis of a first communication mode and asecond wireless communication section performing wireless communicationon the basis of a second communication mode using a different frequencyband from the first communication mode. The computer program causes thecomputer to function as: means for performing wireless communication onthe basis of the first communication mode by using the first wirelesscommunication section; means for performing wireless communication onthe basis of the second communication mode using a different frequencyband from the first communication mode by using the second wirelesscommunication section; means for receiving a beam learning signaltransmitted in the second communication mode in order to specify a beampattern at the time of the communication based on the secondcommunication mode, and monitoring a reception situation for each beampattern; and means for generating and transmitting response informationon the basis of the monitoring result of the reception situation.

According to a seventh embodiment of the invention, a communicationsystem includes a plurality of wireless communication apparatuses thatperform communication on the basis of a first communication mode and asecond communication mode using a different frequency band from thefirst communication mode. The plurality of wireless communicationsapparatus includes a first wireless communication apparatus and a secondwireless communication apparatus. The first wireless communicationapparatus includes a first wireless communication section performingwireless communication on the basis of the first communication mode, asecond wireless communication section performing wireless communicationon the basis of the second communication mode, a beam learning signalgeneration section generating a beam learning signal for specifying abeam pattern at the time of the communication based on the secondcommunication mode and transmitting the beam learning signal from thesecond wireless communication section, a response informationacquisition section acquiring response information responding to thetransmitted beam learning signal, and a preliminary informationgeneration section generating preliminary information so as not to causeinterference among a plurality of wireless communications using thesecond communication mode on the basis of the response information andtransmitting the preliminary information from the first wirelesscommunication section. The second wireless communication apparatusincludes a first wireless communication section performing wirelesscommunication on the basis of the first communication mode, a secondwireless communication section performing wireless communication on thebasis of the second communication mode, a reception situation monitoringsection receiving a beam learning signal transmitted in the secondcommunication mode in order to specify a beam pattern at the time of thecommunication based on the second communication mode, and monitoring areception situation for each beam pattern, and a response informationgeneration section generating and transmitting response information onthe basis of the monitoring result of the reception situation.

Furthermore, the computer program according to the embodiment of theinvention is a computer program that can be provided to a generalcomputer system capable of executing, for example, various program codesthrough computer-readable storage media and communication media. Forexample, the storage media includes optical discs, magnetic discs,semiconductor memories, and the like, and the communication mediaincludes networks and the like. By providing such a computer-readableprogram, processing based on the program is executed in the computersystem.

According to the embodiment of the invention, by performing wirelesscommunication on the basis of the first communication mode and thesecond communication mode using the different frequency band from thefirst communication mode, the beam learning signal for specifying thebeam pattern at the time of the communication based on the secondcommunication mode is transmitted in the second communication mode. Asdescribed later, it is preferable that the frequency band of the firstcommunication mode should be lower than that of the second communicationmode. On the basis of the response information responding to thetransmitted beam learning signal, the preliminary information isgenerated so as not to cause interference among the plurality ofwireless communications using the second communication mode, and thusthe preliminary information is transmitted from the first wirelesscommunication section. Further, in the wireless communication apparatusreceiving the beam learning signal transmitted in the secondcommunication mode, the reception situation is monitored for each beampattern, and the response information is generated and transmitted onthe basis of the monitoring result of the reception situation.

Hence, by optimally setting the beam pattern on the basis of the beamlearning signal and the response information, it is possible to performcommunication in the second communication mode. Further, on the basis ofthe response information, the preliminary information is generated so asnot to cause interference among the plurality of wireless communicationsusing the second communication mode, and thus the preliminaryinformation is transmitted, for example, in the first communication modewhich has a lower frequency band than the second communication mode.Therefore, it is possible to perform communication of the preliminaryinformation with high reliability as compared with the case of using thesecond communication mode. In addition, the preliminary information isgenerated so as not to cause interference among the plurality ofwireless communications. Therefore, on the basis of the preliminaryinformation, it is possible to perform efficient wireless communicationwithout causing interference even when the plurality of wirelesscommunications is performed in the second communication mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an exemplary configuration of awireless communication system;

FIG. 2 is a diagram illustrating an exemplary configuration of awireless communication apparatus;

FIG. 3 is a diagram illustrating an exemplary configuration of awireless communication apparatus;

FIG. 4 is a diagram illustrating an example of a communication procedurefor the case where communication of response information is performed byusing a second communication mode;

FIG. 5 is a diagram illustrating an example of a beam pattern of anantenna;

FIG. 6 is a diagram illustrating an example of a communication procedurefor the case where a beam learning signal sequence is changed inaccordance with the beam pattern;

FIG. 7 is a diagram illustrating an example of a communication procedurefor the case where communication of response information is performed byusing a first communication mode;

FIG. 8 is a diagram illustrating an example of a communication procedurefor the case where the communication of the beam learning signal and thecommunication of the response information are performedbi-directionally;

FIG. 9 is a diagram illustrating an example of a communication procedureby which time efficiency can be improved;

FIG. 10 is a diagram illustrating a case where three wirelesscommunication apparatuses constitute a wireless communication system;

FIG. 11 is a diagram illustrating a case where five wirelesscommunication apparatuses constitute a wireless communication system;

FIG. 12 is a diagram illustrating an example of a schedule table;

FIG. 13 is a flowchart illustrating an example of a transmission processof preliminary information;

FIG. 14 is a diagram illustrating an example of a communicationprocedure (first) for the case where communication is performed on thebasis of the preliminary information;

FIG. 15 is a diagram illustrating an example of a communicationprocedure (second) for the case where communication is performed on thebasis of the preliminary information; and

FIG. 16 is a diagram illustrating an exemplary configuration ofinformation equipment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments will be described. The wirelesscommunication system using the millimeter wave forms a pointed antennadirectivity (that is, beam-shaped antenna directivity) by using aplurality of transmission/reception antennas, and thus it is possible toenlarge the communication range. However, it is possible to increase thecommunication distance by directing the beam to the direction of thecommunication target location, but it is difficult to synchronizepackets in a step of not directing the beam. For example, at the time ofnew entry to a network or at the time of change in location relative tothe communication target caused by movement of a terminal and the like,it is difficult to synchronize packets. Hence, it is difficult even todetect arrival of packets.

Accordingly, in a wireless communication system according to anembodiment of the invention, directivity is changed for each one packetand the packets are transmitted in the second communication mode fromthe transmission side in order to select an optimal beam pattern, by thecombined use of the first communication mode and the second wirelessmode using a different frequency band from the first communication mode.The reception side estimates that the transmission side employs a beampattern with a desirable directivity when the reception side is able toreceive packets. Further, the first communication mode is used beforethe wireless communication is performed by using the beam pattern withthe desirable directivity, thereby performing communication ofpreliminary information with high reliability. Furthermore, thepreliminary information is generated so as not to cause interferenceamong the plurality of wireless communications using the secondcommunication mode.

The first communication mode uses, for example, the microwave (5 GHzband and the like) which is prescribed by IEEE802.11a/b/g having comeinto widespread use as a wireless LAN standard. Further, the secondcommunication mode uses a frequency band higher than that of the firstcommunication mode, for example, the millimeter wave (60 GHz band)prescribed by the VHT (Very High Throughput) standard.

The first communication mode using the microwave is disadvantageous instraightness, and attenuation at the time of reflection is small, ascompared with the mode using the millimeter wave. Therefore, it ispossible to perform the communication of the preliminary informationwith high reliability. Further, since the second communication mode usesthe millimeter wave, the straightness is excellent, and the attenuationat the time of reflection is large. Hence, it is possible to performwireless communication at a high transmission rate by directing thetransmission beam and reception beam toward the communication target. Inaddition, by performing wireless communication on the basis of thepreliminary information, it is possible to perform the plurality ofwireless communications without causing interference in the secondcommunication mode. Therefore, it is possible to perform efficientwireless communication. Furthermore, the first and second communicationmodes are not limited to the specific frequency band like 5 GHz band or60 GHz band. The description will be given in the following order.

1. First Embodiment (two wireless communication apparatuses are used)

2. Second Embodiment (three or more wireless communication apparatusesare used)

1. First Embodiment

Configuration of Wireless Communication System

FIG. 1 shows an exemplary configuration of a wireless communicationsystem. The wireless communication system 10 includes a wirelesscommunication apparatus 20 and a wireless communication apparatus 30.

The wireless communication apparatuses 20 and 30 are configured toperform wireless communication to each other by using both the firstcommunication mode and the second communication mode mentioned above.The first communication mode using the microwave is disadvantageous instraightness, and attenuation at the time of reflection is small, ascompared with the mode using the millimeter wave. Accordingly, when thewireless communication apparatuses 20 and 30 performs the wirelesscommunication on the basis of the first communication mode, theapparatuses are able to communicate with each other without consideringthe directivity of the transmission beam and the reception beam. On theother hand, since the second communication mode uses millimeter wave,the straightness is excellent, and the attenuation at the time ofreflection is large. When the wireless communication apparatuses 20 and30 performs the wireless communication on the basis of the secondcommunication mode, it is more preferable to transmit and receivewireless signals by directing the transmission beam and the receptionbeam toward each communication target.

FIG. 2 shows an exemplary configuration of the wireless communicationapparatus 20. The wireless communication apparatus 20 may be operated asa broadband router or a wireless access point.

The wireless communication apparatus 20 includes antennas 201 and 202, atransmission/reception switch section 203, a frequency conversionsection 204, a directivity control section 205, a beam learning signalgeneration section 208, a modem section 211, a response informationacquisition section 212, and a preliminary information generationsection 213. Further, the wireless communication apparatus 20 includes areception situation monitoring section 215, a transmission data encodingsection 221, and a reception data decoding section 222.

The antenna 201 is an antenna used when the wireless communication isperformed in the first communication mode. The antenna 201 transmits thepreliminary information, which is for performing the communication basedon the second communication mode by using the antenna 202, on the basisof the first communication mode. Further, the antenna 201 receives thesignal transmitted in the first communication mode.

The antenna 202 is an antenna used when the wireless communication isperformed in the second communication mode. The antenna 202 isconfigured so that the directivity can be changed by the directivitycontrol section 205 to be described later. For example, the antenna 202is configured to include a plurality of antennas, and the antenna usedin transmission/reception is changed or the weighting of the signal isadjusted, thereby changing the directivity. Further, a sector is changedby using a sector switching antenna as the antenna 202, and thereby thedirectivity may be changed. The antenna 202 transmits a beam learningsignal for learning an appropriate beam pattern or data signaltransmitted at a high transmission rate on the basis of the secondcommunication mode. Further, the antenna 202 receives information datatransmitted in the second communication mode.

The transmission/reception switch section 203 provides the transmissionsignal of the first communication mode provided from the frequencyconversion section 204 to the antenna 201, and provides the transmissionsignal of the second communication mode to the antenna 202. Further, thetransmission/reception switch section 203 provides the reception signalof the first communication mode obtained by the antenna 201 and thereception signal of the second communication mode obtained by theantenna 202 to the frequency conversion section 204.

The frequency conversion section 204 converts the transmission signal,which is provided from the directivity control section 205, into asignal with a wireless frequency corresponding to the firstcommunication mode or second communication mode, and outputs the signalto the transmission/reception switch section 203. Further, the frequencyconversion section 204 converts the wireless frequency signal, which isprovided from the transmission/reception switch section 203, into anintermediate frequency signal, and outputs the signal to the directivitycontrol section 205.

The directivity control section 205 changes the beam pattern of theantenna 202. Further, when the optimal beam pattern of the antenna 202in the transmission of the wireless signal is discriminated, thedirectivity control section 205 outputs the beam learning signal, whichis provided from the beam learning signal generation section 208 to bedescribed later, to the frequency conversion section 204. Furthermore,the beam learning signal is a signal transmitted when the optimal beampattern is estimated.

The directivity control section 205 performs processing on the beamlearning signal so as to enable identification as to which beam patternof the antenna 202 the beam learning signal is transmitted with. Forexample, the directivity control section 205 adds a pattern identifier,which corresponds to the beam pattern of the antenna 202, to the beamlearning signal. Further, for example, the directivity control section205 may change a beam learning signal sequence in response to the beampattern of the antenna 202. By performing such processing, the wirelesscommunication apparatus receiving the beam learning signal is able todiscriminate the beam pattern of the antenna 202 in thetransmission-side wireless communication apparatus from the patternidentifier or the beam learning signal sequence of the reception signal.Furthermore, the beam learning signal generation section 208 maygenerate the beam learning signal so as to enable identification as towhich beam pattern is used in the transmission.

Further, the directivity control section 205 outputs the receptionsignal, which is provided from the frequency conversion section 204, tothe modem section 211. Further, when the optimal beam pattern of theantenna 202 in the reception of the wireless signal is discriminated,the directivity control section 205 outputs the reception signal, whichis provided from the frequency conversion section 204, and theinformation, which represents the beam pattern of the antenna 202, tothe reception situation monitoring section 215.

The beam learning signal generation section 208 generates the beamlearning signal and outputs the signal to the directivity controlsection 205 when the optimal beam pattern of the antenna 202 isestimated.

The modem section 211 performs a demodulation process on the signalwhich is received by the antennas 201 and 202. Further, the modemsection 211 performs a modulation process on the signal whichtransmitted from the antennas 201 and 202. The modem section 211demodulates the signal, which is received by the antenna 201, in thedemodulation mode used in the first communication mode, and demodulatesthe signal, which is received by the antenna 202, in the demodulationmode used in the second communication mode. When the beam pattern isbeing estimated, the modem section 211 outputs the demodulated receptionsignal to the response information acquisition section 212. After theestimation of the beam pattern is completed, the modem section 211outputs the demodulated reception signal to the reception data decodingsection 222.

Further, the modem section 211 modulates the preliminary information,which is provided from the preliminary information generation section213, on the basis of the modulation mode used in the first communicationmode, and outputs the information to the directivity control section205. Then, the modem section 211 modulates the transmission data, whichis provided from the transmission data encoding section 221, on thebasis of the modulation mode used in the second communication mode, andoutputs the data to the directivity control section 205.

The response information acquisition section 212 decodes the signalprovided from the modem section 211, and acquires the responseinformation from the wireless communication apparatus receiving the beamlearning signal. Further, the response information acquisition section212 provides the acquired response information to the preliminaryinformation generation section 213.

The response information is, as described later, information which isgenerated on the basis of the monitoring result of the receptionsituation monitored in the reception situation monitoring section 315 ofthe wireless communication apparatus 30, and includes informationenabling identification of the beam pattern by which the receptionsituation is optimized.

The preliminary information generation section 213 generates thepreliminary information on the basis of the response information whichis notified from the response information acquisition section 212. Thepreliminary information is information for performing the plurality ofwireless communications using the second communication mode withoutcausing interference. The preliminary information represents scheduledtransmission/reception timing of the wireless communication apparatus,electric power of the scheduled transmission of the wirelesscommunication apparatus, a modulation mode or an encoding mode in thescheduled transmission of the wireless communication apparatus, atransmission/reception directivity beam pattern, and the like.

The reception situation monitoring section 215 monitors the receptionsignal on the basis of the signal which is provided through thedirectivity control section 205. The reception situation monitoringsection 215 discriminates the beam pattern having the best receptioncharacteristics at the time of the reception from a received power ofthe reception signal for each beam pattern, a signal-to-noise ratio, andthe like. For example, the antenna 202 is configured to include aplurality of antennas, and the weighting of the signal, which isreceived by the directivity control section 205, is adjusted, therebygenerating the reception signal for each beam pattern. The receptionsituation monitoring section 215 selects the signal, of which thereceived power is largest and the signal-to-noise ratio and the like arefavorable, from the reception signal for each beam pattern. Then, thereception situation monitoring section 215 sets the beam pattern, whichcorresponds to the selected reception signal, as the beam pattern at thetime of the reception in the communication with the wirelesscommunication apparatus which transmits the response information.

The transmission data encoding section 221 encodes the transmission datatransmitted in the second communication mode, that is, the data signaltransmitted at a high transmission rate by using the encoding mode whichis represented by the preliminary information, and outputs the same tothe modem section 211. Further, the reception data decoding section 222decodes the reception data, which is provided from the modem section211, by using the encoding mode which is represented by the preliminaryinformation.

FIG. 3 shows an exemplary configuration of the wireless communicationapparatus 30. The wireless communication apparatus 30 includes anantennas 301 and 302, a transmission/reception switch section 303, afrequency conversion section 304, a directivity control section 305, amodem section 311, a reception situation monitoring section 315, aresponse information generation section 316, and a preliminaryinformation acquisition section 317. Further, the wireless communicationapparatus 30 includes a transmission data encoding section 321 and areception data decoding section 322.

The antenna 301 is an antenna used when the wireless communication isperformed in the first communication mode. The antenna 301 receives thepreliminary information transmitted in the first communication mode.

The antenna 302 is an antenna used when the wireless communication isperformed in the second communication mode. The antenna 302 isconfigured so that the directivity can be changed by the directivitycontrol section to be described later. For example, the antenna 302 isconfigured to include a plurality of antennas, and the antenna used intransmission/reception is changed or the weighting of the signal isadjusted, thereby changing the directivity. Further, a sector is changedby using a sector switching antenna as the antenna 302, and thereby thedirectivity may be changed. The antenna 302 receives the beam learningsignal and the data transmitted in the second communication mode.Further, the antenna 302 transmits the data signal, which is transmittedat a high transmission rate, in the second communication mode.

In addition, the antenna 301 or the antenna 302 transmits the responseinformation in order to perform communication in the secondcommunication mode. For example, when the response information istransmitted from the antenna 301, the information is transmitted in thefirst communication mode. In addition, when the response information istransmitted from the antenna 302, the information is transmitted in thesecond communication mode.

The transmission/reception switch section 303 provides the transmissionsignal of the first communication mode provided from the frequencyconversion section 304 to the antenna 301, and provides the transmissionsignal of the second communication mode to the antenna 302. Further, thetransmission/reception switch section 303 provides the reception signalof the first communication mode obtained by the antenna 301 and thereception signal of the second communication mode obtained by theantenna 302 to the frequency conversion section 304.

The frequency conversion section 304 converts the transmission signal,which is provided from the directivity control section 305, into asignal with a wireless frequency corresponding to the firstcommunication mode or second communication mode, and outputs the signalto the transmission/reception switch section 303. Further, the frequencyconversion section 304 converts the wireless frequency signal, which isprovided from the transmission/reception switch section 303, into anintermediate frequency signal, and outputs the signal to the directivitycontrol section 305.

The directivity control section 305 changes the beam pattern of theantenna 302. Further, the directivity control section 305 outputs theintermediate frequency signal, which is provided from the frequencyconversion section 304, to the modem section 311. Further, when theoptimal beam pattern of the antenna 302 in the reception of the wirelesssignal is discriminated, the directivity control section 305 outputs theintermediate frequency signal, which is provided from the frequencyconversion section 304, and the information, which represents the beampattern of the antenna 302, to the reception situation monitoringsection 315.

The modem section 311 performs a demodulation process on the signalwhich is received by the antennas 301 and 302. Further, the modemsection 311 performs a modulation process on the signal whichtransmitted from the antennas 301 and 302. The modem section 311demodulates the signal, which is received by the antenna 301, in thedemodulation mode used in the first communication mode, and demodulatesthe signal, which is received by the antenna 302, in the demodulationmode used in the second communication mode. When the beam pattern isbeing estimated, the modem section 311 modulates the responseinformation, which is generated by the response information generationsection 316 to be described later, on the basis of the modulation modeused in the first or second communication mode, and outputs theinformation to the directivity control section 305. For example, whenthe response information is transmitted from the antenna 301, the modemsection 311 modulates the response information on the basis of themodulation mode used in the first communication mode. In addition, whenthe response information is transmitted from the antenna 302, the modemsection 311 modulates the response information on the basis of themodulation mode used in the second communication mode. After theestimation of the beam pattern is completed, the modem section 311outputs the demodulated reception signal to the reception data decodingsection 322. Further, the modem section 311 modulates the transmissiondata, which is provided from the transmission data encoding section 321,on the basis of the modulation mode used in the second communicationmode, and outputs the data to the directivity control section 305.

The reception situation monitoring section 315 monitors the receptionsignal on the basis of the signal which is provided through thedirectivity control section 305. The reception situation monitoringsection 315 measures a received power of the reception signal for eachbeam pattern, a signal-to-noise ratio, and the like. The receptionsituation monitoring section 315 may discriminate the beam patternhaving the best reception characteristics at the time of the receptionfrom a received power of the reception signal for each beam pattern, asignal-to-noise ratio, and the like. For example, the antenna 302 isconfigured to include a plurality of antennas, and the weighting of thesignal, which is received by the directivity control section 305, isadjusted, thereby generating the reception signal for each beam pattern.The reception situation monitoring section 315 selects the signal, ofwhich the received power is largest and the signal-to-noise ratio andthe like are favorable, from the reception signal for each beam pattern.Then, the reception situation monitoring section 315 sets the beampattern, which corresponds to the selected reception signal, as the beampattern at the time of the reception in the communication with thewireless communication apparatus which transmits the responseinformation.

Further, when the beam learning signal is received with the beam patternat the time of the reception, the reception situation monitoring section315 provides the monitoring result of the received power and thesignal-to-noise ratio, the beam learning signal sequence and the patternidentifier obtained when the reception situation is most favorable tothe response information generation section 316.

The response information generation section 316 generates the responseinformation on the basis of the monitoring result of the receptionsituation which is monitored by the reception situation monitoringsection 315. The response information includes information enablingidentification of the beam pattern by which the reception situation isoptimized. For example, the response information may represent a part ofor all of the received power for each beam pattern. Further, theresponse information may include the signal-to-noise ratio of the partof or all of the signal monitored by the reception situation monitoringsection, the pattern identifier of a part of or all of the beam patternobtained when the reception situation monitored by the receptionsituation monitoring section is favorable, the beam learning signalsequence, and the like. Further, the response information may includeinformation representing that communication is not available with anybeam pattern. Furthermore, the response information is not limited tothose, and it may be possible to notify different information if theinformation enables identification of the beam pattern by which thereception situation is optimized.

The preliminary information acquisition section 317 decodes the signalwhich is provided from the modem section 211, and acquires thepreliminary information which is transmitted from the wirelesscommunication apparatus 20. Further, on the basis of the preliminaryinformation, the preliminary information acquisition section 317configures the settings for the transmission/reception timing, thetransmitted power, the modulation mode and the encoding mode in thetransmission, the transmission/reception directivity beam pattern, andthe like.

The transmission data encoding section 321 encodes the transmission datatransmitted in the second communication mode, that is, the data signaltransmitted at a high transmission rate by using the encoding mode whichis represented by the preliminary information, and outputs the same tothe modem section 311. Further, the reception data decoding section 322decodes the reception data, which is provided from the modem section311, by using the encoding mode which is represented by the preliminaryinformation.

Furthermore, the first wireless communication section, which performswireless communication in the first communication mode, includes theantennas 201 and 301, the transmission/reception switch sections 203 and303, the frequency conversion sections 204 and 304, and the like.Further, the second wireless communication section, which performswireless the antennas 202 and 302 in the second communication mode,includes the transmission/reception switch sections 203 and 303, thefrequency conversion sections 204 and 304, the directivity controlsections 205 and 305, and the like.

In addition, the configurations of the wireless communicationapparatuses 20 and 30 are not limited to the configurations shown inFIGS. 2 and 3. For example, it may be possible to adopt a configurationin which the wireless communication apparatuses 20 and 30 is providedwith the beam learning signal generation section, the responseinformation acquisition section, and the response information generationsection so that any one of the wireless communication apparatuses 20 and30 is able to transmit the beam learning signal and the responseinformation. Further, each of the wireless communication apparatuses 20and 30 may be provided with the preliminary information generationsection and the preliminary information acquisition section so that theconfigurations of those are made to be common. In this case, when thewireless communication apparatus 20 manages the communication, thepreliminary information generation section of the wireless communicationapparatus 20 and the preliminary information acquisition section of thewireless communication apparatus 30 are operated.

Next, the operation of the wireless communication system 10 isdescribed. The wireless communication system 10 performs thetransmission of the data signals between the wireless communicationapparatus 20 and the wireless communication apparatus 30. In this case,the wireless communication system 10 performs a training process forsetting the beam pattern of the antenna used in the second communicationmode to be an optimal state and the communication process of thepreliminary information before the communication of the data signal.

In the training process, the wireless communication apparatus 20generates the beam learning signal for specifying the beam pattern atthe time of the communication based on the second communication mode,and transmits the signal in the second communication mode. The wirelesscommunication apparatus 30 receives the beam learning signal, andmonitors the reception situation for each beam pattern, therebygenerating and transmitting response information on the basis of themonitoring result. The wireless communication apparatus 20 discriminatesthe optimal beam pattern on the basis of the response informationresponding to the beam learning signal.

In the communication process of the preliminary information, thewireless communication apparatus 20, on the basis of the responseinformation, generates the preliminary information so as not to causeinterference among the plurality of wireless communications using thesecond communication mode, and transmits the information in the firstcommunication mode. Further, the wireless communication apparatus 30, onthe basis of the received preliminary information, performscommunication of the data signal in the second communication mode.

FIG. 4 shows an example of a communication procedure for the case wherethe communication of the response information is performed by using thesecond communication mode. Furthermore, in FIG. 4, the frequency channelF1 is a frequency channel used in the first communication mode, and thefrequency channel F2 has a frequency different from that of thefrequency channel F1, and is a frequency channel used in the secondcommunication mode.

The wireless communication apparatus 20 transmits the beam learningsignal to the frequency channel F2 in order to monitor the receptionsituation for each beam pattern of the antenna. In this case, thedirectivity control section 205 of the wireless communication apparatus20 sets the number of times of transmission of the beam learning signalor the beam learning signal sequence in accordance with the number ofbeam patterns.

FIG. 5 shows an example of the beam pattern of the antenna 202. When thebeam pattern of the antenna 202 can be changed into any one of thepatterns PT1 (directivity 1) to PT4 (directivity 4), the wirelesscommunication apparatus 20 transmits the beam learning signals inaccordance with the respective beam patterns as shown in FIG. 4. Thatis, the beam learning signals are transmitted four times. Further, thewireless communication apparatus 20 adds the pattern identifier orchange the beam learning signal sequence so as to identify which one ofthe beam patterns is used in the transmission from the beam learningsignal.

The wireless communication apparatus 30 receives the beam learningsignal, and discriminates the beam learning signal or the beam patternby which the reception signal is optimized. Then, the wirelesscommunication apparatus 30 generates the response information enablingdiscrimination as to the beam pattern by which the reception signal isoptimized, and transmits the information through the frequency channelF2. Furthermore, the beam pattern of the antenna 302 at this time is setas, for example, a pattern which is obtained when the beam learningsignal is received most favorably.

The wireless communication apparatus 20 receives the responseinformation, and discriminates the optimal beam pattern at the time oftransmitting the data signal from the antenna 202 to the wirelesscommunication apparatus 30 through the frequency channel F2 on the basisof the received response information.

Further, the wireless communication apparatus 20 generates thepreliminary information, and transmits the generated preliminaryinformation from the antenna 201 through the frequency channel F1. Then,the wireless communication apparatus 20 transmits and receives the datasignals through the frequency channel 2 in accordance with the generatedpreliminary information.

The wireless communication apparatus 30 allows the antenna 301 toreceive the preliminary information, and transmits and receives the datasignals through the frequency channel 2 in accordance with the receivedpreliminary information.

Furthermore, FIG. 4 shows the case where the communication is performedby using two frequency channels, but the communication may be performedby using more frequency channels. In this case, it is preferable thatthe frequency channel used in the communication of the preliminaryinformation should be set as a channel of which the frequency is lowerthan that of the frequency channel used in the communication of the datasignal.

As described above, when the communication is performed by using two ormore frequency channels, it is preferable that the frequency channelused in the communication of the preliminary information should be setas a channel of which the frequency is lower than that of the frequencychannel used in the communication of the data signal. That is, it ispreferable that the frequency band of the first communication modeshould be lower than the frequency band of the second communicationmode. In such a manner, it is possible to stably transmit and receivethe preliminary information that should be more reliably exchanged.

FIG. 6 shows an example of a communication procedure for the case wherethe beam learning signal sequence is changed in accordance with the beampattern in a single beam learning signal at the time of transmitting thebeam learning signal through the frequency channel F2. As describedabove, in the single beam learning signal, the beam learning signalsequence is changed in accordance with the beam pattern, and then it ispossible to avoid loss of frame efficiency. Further, owing to theposition in the packet at which the reception signal is optimized whenthe beam learning signal is received, it is possible to perform theidentification of the beam pattern.

FIG. 7 shows an example of a communication procedure for the case wherethe communication of the response information is performed by using thefirst communication mode. When the communication is performed by usingtwo or more frequency channels, it is preferable that the frequencychannel used in the communication of the response information should beset as a channel of which the frequency is lower than that of thefrequency channel used in the communication of the data signal. Forexample, the frequency channel F1 used in the first communication modeis set as a microwave frequency channel, and the frequency channel F2used in the second communication mode is set as a millimeter-wavefrequency channel. In this case, since straightness of the microwave isnot greater than that of the millimeter wave, it is possible to stablytransmit and receive the response information that should be morereliably exchanged. Further, the communication is available even if thebeam pattern is not set to be optimal similarly to the case where thecommunication is performed through the frequency channel F2.Accordingly, it is also possible to transmit the response informationfor each beam learning signal. Further, it is also possible to transmitthe response information whenever trainings are terminated apredetermined number of times.

FIG. 8 shows a communication procedure for the case where thecommunication of the beam learning signal and the communication of theresponse information are performed bi-directionally between the wirelesscommunication apparatus 20 and the wireless communication apparatus 30.In this case, as described above, each of the wireless communicationapparatuses 20 and 30 is provided with the beam learning signalgeneration section, the response information acquisition section, andthe response information generation section. In FIGS. 4, 6, and 7,depending on the reception situation of when the beam learning signaltransmitted from the wireless communication apparatus 20 is received bythe wireless communication apparatus 30, the beam pattern at the time ofthe transmission in the wireless communication apparatus 20 and the beampattern at the time of the reception in the wireless communicationapparatus 30 are determined. Further, by using the beam pattern, thetransmission is performed by the antenna 302 and the reception isperformed by the antenna 202. However, it is conceivable that, dependingon the communication situation and the like, the optimal beam patternsof the transmission performed by the antenna 302 and the receptionperformed by the antenna 202 are different from the optimal beampatterns of the reception performed by the antenna 302 and thetransmission performed by the antenna 202.

In this case, depending on the reception situation of when the beamlearning signal is transmitted from the wireless communication apparatus30 and the beam learning signal is received by the wirelesscommunication apparatus 20, the beam pattern at the time of thetransmission in the wireless communication apparatus 30 and the beampattern at the time of the reception in the wireless communicationapparatus 20 are determined. As described above, when the beam patternsare determined, it is possible to optimize the beam patterns in therespective cases where the data signal is transmitted from the wirelesscommunication apparatus 20 to the wireless communication apparatus 30and the data signal is transmitted from the wireless communicationapparatus 30 to the wireless communication apparatus 20.

FIG. 9 shows an example of a communication procedure capable ofimproving time efficiency in the case where the communication of thebeam learning signal and the communication of the response informationare performed bi-directionally. The wireless communication apparatus 30adds the beam learning signal to the response information and transmitsthe information when the response information is transmitted.

As described above, when the response information and the beam learningsignal are unified, in the training process, it is possible to reducethe number of times of the transmission/reception between the wirelesscommunication apparatus 20 and the wireless communication apparatus 30,and it is possible to improve the time efficiency.

2. Second Embodiment

FIG. 10 shows the case where three wireless communication apparatusesconstitute a wireless communication system. The wireless communicationsystem 10 a includes a wireless communication apparatus 20 and twowireless communication apparatuses 30-1 and 30-2. Further, the wirelesscommunication apparatuses 30-1 and 30-2 are configured to be the same asthe wireless communication apparatus 30 shown in FIG. 3.

Here, the wireless communication apparatus 20 is able to communicatewith the wireless communication apparatuses 30-1 and 30-2. Further, thewireless communication apparatus 30-1 is able to communicate with thewireless communication apparatuses 20 and 30-2. The wirelesscommunication apparatus 30-2 is able to communicate with the wirelesscommunication apparatuses 20 and 30-1.

In this case, for example, between the wireless communication apparatus20 and the wireless communication apparatus 30-1, not only theinformation of the reception situation for each beam pattern between thewireless communication apparatuses 20 and 30-1 but also the informationof the reception situation for each beam pattern between the wirelesscommunication apparatuses 30-1 and 30-2 are treated as the responseinformation. As described above, when a configuration is made so as toacquire the response information in communication in which the ownwireless communication apparatus is not interposed, it is possible togenerate the preliminary information capable of efficiently performingthe wireless communication.

Here, in order to facilitate the efficient wireless communication, forexample the case where five wireless communication apparatusesconstitute a wireless communication system is described in detail. FIG.11 shows the case where five wireless communication apparatusesconstitute a wireless communication system. The wireless communicationsystem 10 b includes a wireless communication apparatus 20 and fourwireless communication apparatuses 30-1 to 30-4. Further, the wirelesscommunication apparatuses 30-1 to 30-4 are configured to be the same asthe wireless communication apparatus 30 shown in FIG. 3.

The wireless communication apparatus 20 generates a schedule table onthe basis of the response information. The schedule table is, forexample, a matrix table representing whether or not communication isavailable between the wireless communication apparatuses.

Here, as shown in FIG. 11, the wireless communication apparatus 20 isable to communicate with, for example, the four wireless communicationapparatuses 30-1 to 30-4 by using the frequency channel F2 in the secondcommunication mode. Further, between the wireless communicationapparatus 30-1 and the wireless communication apparatus 30-2 and betweenthe wireless communication apparatus 30-3 and the wireless communicationapparatus 30-4, communication is available by using the frequencychannel F2 in the second communication mode. Then, among the wirelesscommunication apparatus 30-1 and the wireless communication apparatuses30-3 and 30-4 and among the wireless communication apparatus 30-2 andthe wireless communication apparatuses 30-3 and 30-4, the communicationis unavailable by using the frequency channel F2 in the secondcommunication mode.

The wireless communication apparatus 20 is able to acquire the responseinformation of the communication in which the own wireless communicationapparatus is not interposed. That is, the wireless communicationapparatuses 30-1 to 30-4 transmits the response information, which isgenerated by the response information generation section, including theinformation representing the available wireless communication apparatus.For example, the response information, which is provided from thewireless communication apparatus 30-1 to the wireless communicationapparatus 20, includes the response information which is provided fromthe wireless communication apparatuses 30-2, 30-3, and 30-4 to thewireless communication apparatus 30-1. Further, the responseinformation, which is provided from the wireless communicationapparatuses 30-2, 30-3, and 30-4 to the wireless communication apparatus20, includes the response information of the communication in which thewireless communication apparatus 20 is not interposed. Further, theresponse information is not limited to this, and may include theidentification information uniquely allocated to the available wirelesscommunication apparatus.

As described above, the wireless communication apparatus 20 is able todetect a communication path in which the own wireless communicationapparatus is not interposed on the basis of the response informationfrom the wireless communication apparatuses 30-1 to 30-4. Accordingly,on the basis of the response information of the wireless communicationapparatus 20, the schedule table shown in FIG. 12 can be generated.Furthermore, in FIG. 12, the reference sign O represents that thecommunication is available, and the reference sign X represents that thecommunication is unavailable.

The wireless communication apparatus 20 generates the preliminaryinformation representing the communication schedule and the like set soas not to cause interference by using the generated schedule table, andtransmits the generated preliminary information to the wirelesscommunication apparatus. For example, the wireless communicationapparatus 30-1 is able to communicate with only the wirelesscommunication apparatus 20 and the wireless communication apparatus30-2, and the wireless communication apparatus 30-2 is able tocommunicate with only the wireless communication apparatus 20 and thewireless communication apparatus 30-1. On the other hand, the wirelesscommunication apparatus 30-3 is able to communicate with only thewireless communication apparatus 20 and the wireless communicationapparatus 30-4, and the wireless communication apparatus 30-4 is able tocommunicate with only the wireless communication apparatus 20 and thewireless communication apparatus 30-3. That is, the communicationbetween the wireless communication apparatus 30-1 and the wirelesscommunication apparatus 30-2 does not interfere with the communicationbetween the wireless communication apparatus 30-3 and the wirelesscommunication apparatus 30-4. Accordingly, the wireless communicationapparatus 20 is able to determine the communication schedule so as toconcurrently perform the communication between the wirelesscommunication apparatus 30-1 and the wireless communication apparatus30-2 and the communication between the wireless communication apparatus30-3 and the wireless communication apparatus 30-4 at the same time.

FIG. 13 is a flowchart illustrating an example of the transmissionprocess of the preliminary information. In step ST1, the wirelesscommunication apparatus 20 transmits the beam learning signal. Thewireless communication apparatus 20 transmits the beam learning signalby using the frequency channel F2, and the flow advances to step ST2.

In step ST2, the wireless communication apparatus 20 generates theschedule table. The wireless communication apparatus 20 receives theresponse information which is provided from another wirelesscommunication apparatus in response to the transmission of the beamlearning signal. Further, the wireless communication apparatus 20generates the schedule table on the basis of the received responseinformation, and the flow advances to step ST3.

In step ST3, the wireless communication apparatus 20 determines whetheror not the communication request exists. In the wireless communicationapparatus 20, if there is no communication request, the flow returns tostep ST3, and if there is the communication request, the flow advancesto step ST4.

In step ST4, the wireless communication apparatus 20 starts generatingthe preliminary information, and the flow advances to step ST5.

In step ST5, the wireless communication apparatus 20 determines whetheror not the communication is available without causing interference. Ifthe wireless communication apparatus 20 determines that thecommunication is available without causing interference with anothercommunication during the communication for the request on the basis ofthe schedule table, the flow advances to step ST6. In contrast, if it isdetermined that the communication is unavailable without causinginterference with another communication, the flow advances to step ST7.

In step ST6, the wireless communication apparatus 20 configures thesetting for transmission opportunity. When it is possible to performcommunication without causing interference with another communication,the wireless communication apparatus 20 generates the preliminaryinformation on the communication corresponding to the request, and theflow returns to step ST4.

In step ST7, the wireless communication apparatus 20 terminates thegeneration of the preliminary information, and the flow advances to stepST8. The wireless communication apparatus 20 performs the processes ofsteps ST5 and ST6, and thus is able to set the communication schedulefor the plurality of communications performed without interference.Further, the setting of the communication schedule for the plurality ofcommunication performed without interference is completed, and then theflow advances from steps ST5 to ST7, and the generation of thepreliminary information is terminated.

In step ST8, the wireless communication apparatus 20 transmits thepreliminary information. The wireless communication apparatus 20transmits the preliminary information, which is generated by theprocesses of steps ST4 to ST7, to another wireless communicationapparatus.

As described above, when the process shown in FIG. 13 is performed, thewireless communication apparatuses perform communication on the basis ofthe preliminary information. In such a manner, it is possible tomultiply perform the plurality of communications with the same frequencychannel and at the same time without causing interference with anothercommunication.

FIGS. 14 and 15 show examples of communication procedures for the casewhere communication is performed on the basis of the preliminaryinformation which is created by using the schedule table of FIG. 12.When the preliminary information created by the wireless communicationapparatus 20 is notified to another wireless communication apparatus,the apparatus stably transmits and receives the preliminary informationthat should be more reliably exchanged. Then, the apparatus transmitsthe preliminary information through the frequency channel F1 lower thanthe frequency channel F2 through which the communication of the datasignal is performed.

The preliminary information may include the scheduledtransmission/reception timing of the apparatus. Further, the preliminaryinformation may include the transmitted power of the scheduledtransmission of the apparatus, the modulation mode of the scheduledtransmission of the apparatus, and the encoding mode of the scheduledtransmission of the apparatus. In addition, the preliminary informationmay include the antenna beam pattern used in the scheduledtransmission/reception of the apparatus.

Furthermore, FIG. 14 shows the case where the preliminary information istransmitted from the wireless communication apparatus 20 in a broadcastmanner. Further, FIG. 15 shows the case where the preliminaryinformation is transmitted from the wireless communication apparatus 20to every wireless communication apparatus in a unicast manner.

FIGS. 14 and 15, for example at the time point t1, communication fromthe wireless communication apparatus 30-2 to the wireless communicationapparatus 30-1 and the communication from the wireless communicationapparatus 30-3 to the wireless communication apparatus 30-4 areperformed through the same frequency channel. The reason why the samefrequency channel is allocated is that it is figured out thatinterference does not occur between the two rather than the priorschedule table. Further, at the time point t2, by setting theappropriate beam pattern of the antenna, it is also possible to performthe communication at the same time and with the same frequency withoutinterference.

In addition, in FIGS. 14 and 15, the timings between the apparatuses atthe time points t1 and t2 are synchronized. Thus, it is figured out thatthe wireless communications are performed at the same time. However, itmay be also possible to schedule the communications asynchronously ifinterference does not occur.

Furthermore, the wireless communication apparatuses 20 and 30 may be awireless communication module provided in a computer device, a portablecellular phone, a portable information terminal such as PDA (PersonalDigital Assistant), a portable music player, information equipment suchas a game machine, a television receiver, or other information householdappliances.

FIG. 16 shows an exemplary configuration of the information equipment 50equipped with the modularized wireless communication apparatuses 20 and30.

A CPU (Central Processing Unit) 51 executes a program stored in a ROM(Read Only Memory) 52 or a storage section 59 under the programexecution environment provided by an operating system (OS). For example,it is possible to realize a process of synchronizing the receivedpackets or a part of the process by allowing the CPU 51 to execute apredetermined program.

The ROM 52 permanently stores program codes such as the POST (Power OnSelf Test) and the BIOS (Basic Input Output System). The RAM (RandomAccess Memory) 53 is used to load a program stored in the ROM 52 or thestorage section 59 when the CPU 51 is intended to execute the program,or to temporarily retain work data of a program in the process ofexecution. Those are connected to each other through a local bus 54directly connected to a local pin of the CPU 51.

The local bus 54 is connected to an input/output interface section 55.The input/output interface section 55 is connected with a user interfacesection 56, an input/output section 57, a display section 58, thestorage section 59, a communication section 60, and a drive 61.

The user interface section 56 includes pointing devices such as akeyboard and a mouse, and generates an operation signal based on theuser's operation. The input/output section 57 is an interface forinputting and outputting various kinds of data from and to externaldevices. The display section 58 includes a LCD (Liquid Crystal Display)or a CRT (Cathode Ray Tube), and displays various information as textsand images. The storage section 59 includes a HDD (Hard Disk Drive) andthe like. The storage section 59 is used to install programs such as anoperating system and various applications executed by the CPU 51 orretain data files.

The communication section 60 is a wireless communication interfaceconstituted by modularizing the wireless communication apparatuses 20and 30. The communication section 60 is operated as an access point or aterminal under the infrastructure mode, or is operated as a terminalunder the ad-hoc mode, and performs the wireless communication withother terminals existing in the communication range.

The drive 61 is for reading out various kinds of data, computerprograms, and the like stored in an equipped removable medium 70 such asa magnetic disc, an optical disc, an optical magnetic disc, or asemiconductor memory.

According to the embodiments of the invention, the wirelesscommunication is performed by using the first communication mode and thesecond communication mode using a different frequency band from thefirst communication mode, and the beam learning signal for specifyingthe beam pattern at the time of performing the communication based onthe second communication mode is transmitted in the second communicationmode. On the basis of the response information responding to thetransmitted beam learning signal, the plurality of wirelesscommunications using the second communication mode generate thepreliminary information so as not to cause interference, and thepreliminary information is transmitted to the first wirelesscommunication section. Further, in the wireless communication apparatusreceiving the beam learning signal transmitted in the secondcommunication mode, the reception situation is monitored for each beampattern, and the response information is generated and transmitted onthe basis of the monitoring result of the reception situation. Hence, bysetting the beam pattern to be optimal on the basis of the beam learningsignal and the response information, it is possible to performcommunication in the second communication mode.

Further, on the basis of the response information, the plurality ofwireless communications using the second communication mode generate thepreliminary information so as not to cause interference, and thepreliminary information is transmitted in the first communication modeusing the different frequency band from the second communication mode.Hence, when the plurality of wireless communications are performed inthe second communication mode on the basis of the preliminaryinformation, it is possible to perform efficient wireless communicationwithout causing interference.

In addition, the wireless communication is performed by setting thefrequency band of the first communication mode to be lower than thefrequency band of the second communication mode. Thus, it is possible tostably transmit and receive the preliminary information that should beexchanged more reliably. For example, the millimeter wave may be used inthe second communication mode so as to transmit a large volume ofinformation. In this case, since the millimeter wave is excellent instraightness, it is difficult to perform communication stably unless thedirectivity of the beam is precisely set in the direction of thecommunication target location. In contrast, a wave having a lowerfrequency than the second communication mode, for example, the microwavemay be used in the first communication mode. In this case, since themicrowave is disadvantageous in straightness as compared with themillimeter wave, it is possible to perform communication stably althoughthe directivity of the beam is not precisely set in the direction of thecommunication target location. Accordingly, when the preliminaryinformation is transmitted in the first communication mode by settingthe frequency band of the first communication mode to be lower than thefrequency band of the second communication mode, it is possible toincrease reliability of the communication of the preliminary informationthat should be exchanged more reliably.

The present application contains subject matter related to thatdisclosed in Japanese Priority Patent Application JP 2009-106214 filedin the Japan Patent Office on Apr. 24, 2009, the entire content of whichis hereby incorporated by reference.

The above described embodiments should not be interpreted as limitingthe scope of the invention. Since the above described embodiments areset forth by way of example, it will be readily apparent to thoseskilled in the art that obvious modifications, derivations andvariations can be made to the embodiments without departing from thescope of the invention. Consequently, in order to understand the scopeof the invention, the claims appended hereto should be considered.

What is claimed is:
 1. A wireless communication apparatus comprising: afirst wireless communication section performing wireless communicationon the basis of a first communication mode; a second wirelesscommunication section performing wireless communication on the basis ofa second communication mode using a different frequency band from thefirst communication mode; a beam learning signal generation sectiongenerating a beam learning signal for specifying a beam pattern at thetime of the communication based on the second communication mode andtransmitting the beam learning signal from the second wirelesscommunication section; a response information acquisition sectionacquiring response information responding to the transmitted beamlearning signal; and a preliminary information generation sectiongenerating preliminary information using the second communication modeon the basis of the response information and transmitting thepreliminary information from the first wireless communication section.2. The wireless communication apparatus according to claim 1, whereinthe preliminary information generation section includes a communicationschedule, which is set not to cause interference in the preliminaryinformation.
 3. The wireless communication apparatus according to claim2, wherein the preliminary information generation section includes acommunication schedule, which is set to perform the plurality ofwireless communications simultaneously without causing interference inthe preliminary information.
 4. The wireless communication apparatusaccording to claim 2, wherein the beam learning signal enablesidentification as to which beam pattern is used in the transmissionthereof, and wherein the second wireless communication section transmitsthe beam learning signal with the beam pattern based on the beamlearning signal in the second communication mode.
 5. The wirelesscommunication apparatus according to claim 2, wherein the first wirelesscommunication section simultaneously or separately transmits thepreliminary information to a plurality of wireless communicationsapparatuses.
 6. The wireless communication apparatus according to claim1, wherein a frequency band of the first communication mode is lowerthan that of the second communication mode.
 7. The wirelesscommunication apparatus according to claim 1, wherein the preliminaryinformation generation section does not alleviate interference among aplurality of wireless communications.
 8. A wireless communication methodcomprising the steps of: performing wireless communication on the basisof a first communication mode, by using a first wireless communicationsection; performing wireless communication on the basis of a secondcommunication mode using a different frequency band from the firstcommunication mode, by using a second wireless communication section;generating a beam learning signal for specifying a beam pattern at thetime of the communication based on the second communication mode andtransmitting the beam learning signal from the second wirelesscommunication section, by using a beam learning signal generationsection; acquiring response information responding to the transmittedbeam learning signal, by using a response information acquisitionsection; and generating preliminary information using the secondcommunication mode on the basis of the response information andtransmitting the preliminary information from the first wirelesscommunication section, by using a preliminary information generationsection.
 9. A non-transitory, computer readable medium comprisinginstructions for causing a computer to execute a communication processin a communication apparatus including a first wireless communicationsection performing wireless communication on the basis of a firstcommunication mode and a second wireless communication sectionperforming wireless communication on the basis of a second communicationmode using a different frequency band from the first communication mode,the computer program causing the computer to function as: means forperforming wireless communication on the basis of the firstcommunication mode by using the first wireless communication section;means for performing wireless communication on the basis of the secondcommunication mode using a different frequency band from the firstcommunication mode by using the second wireless communication section;means for generating a beam learning signal for specifying a beampattern at the time of the communication based on the secondcommunication mode and transmitting the beam learning signal from thesecond wireless communication section; means for acquiring responseinformation responding to the transmitted beam learning signal; andmeans for generating preliminary information using the secondcommunication mode on the basis of the response information andtransmitting the preliminary information from the first wirelesscommunication section.
 10. A communication system comprising a pluralityof wireless communication apparatuses that perform communication on thebasis of a first communication mode and a second communication modeusing a different frequency band from the first communication mode,wherein the plurality of wireless communications apparatus includes afirst wireless communication apparatus and a second wirelesscommunication apparatus, wherein the first wireless communicationapparatus includes: a first wireless communication section performingwireless communication on the basis of the first communication mode, asecond wireless communication section performing wireless communicationon the basis of the second communication mode, a beam learning signalgeneration section generating a beam learning signal for specifying abeam pattern at the time of the communication based on the secondcommunication mode and transmitting the beam learning signal from thesecond wireless communication section, a response informationacquisition section acquiring response information responding to thetransmitted beam learning signal, and a preliminary informationgeneration section generating preliminary information using the secondcommunication mode on the basis of the response information andtransmitting the preliminary information from the first wirelesscommunication section, and wherein the second wireless communicationapparatus includes: a first wireless communication section performingwireless communication on the basis of the first communication mode, asecond wireless communication section performing wireless communicationon the basis of the second communication mode, a reception situationmonitoring section receiving a beam learning signal transmitted in thesecond communication mode in order to specify a beam pattern at the timeof the communication based on the second communication mode, andmonitoring a reception situation for each beam pattern, and a responseinformation generation section generating and transmitting responseinformation on the basis of the monitoring result of the receptionsituation.